This invention relates generally to a method and apparatus for facsimile systems and office information systems and more specifically to raster image scanner used to scan and digitize documents.
Office information systems include computers and associated peripherals such as monitors, eg a cathode ray tube (CRT), mass storage devices and printers to keep track of, to manipulate and to distribute information necessary to the activities of an office. Typically, these systems deal only with structured, digital data representing the information. Text and graphic information displayed on a monitor or printed out by a printer are created solely from structured data. In addition, document scanning devices are now being added to such office information systems such as described in U.S. patent application Ser. No. 440,668 filed Nov. 10, 1982, entitled Management Communication Terminal System and having a common inventor with this present patent application. This patent application is incorporated herein by reference.
As described in the patent application cited in the previous paragraph such office information systems now include a graphic data generator in the form of a camera for scanning a document to create a signal representing the information on the document, and the signal may be used to display the document on the video display associated with the scanning camera, or the signal may be stored for future use, or the signal may be transmitted to a remote location for displaying the document via a printer or a video terminal thereat.
Due to cost and other practical considerations these scanning cameras typically utilize a charge coupled device (CCD) linear array and optics and the CCD array and a document are moved relative to each other while each CCD device in the array is periodically and rapidly sampled using a time division multiplexing technique. Each of these samples is then digitized using an analog-to-digital converter to create a digital representation of the document being scanned.
There is one problem in prior art document scanning system utilizing CCD arrays. Using CCD arrays it typically takes several seconds to completely scan a document. Then the digitized information resulting from the scanning process is used to redisplay the document on the video display or a printer to verify that the desired portions of the document has been scanned. Normally this is not the case and the document must be repositioned and the scanning process repeated with the results again being checked. This process is often repeated several times in order to properly position a document under the scanning device to scan the desired portion of the document. This can take an inordinate amount of time which is unacceptable to a busy executive.
The Applicants' have solved this problem in the prior art by provided a method and apparatus for quickly and easily positioning a document only once and the desired portion of the document will be scanned and digitized the first scan.